On Thu, Feb 6, 2025 at 04:39 PM, Mike M wrote:
Just compared 2SC5551 to 2SC3357 in an LZ1AQ amp. There is almost no difference in IP2/IP3 and frequency response.
My simulation results mirror your experimental(??) findings. There is negligible IP3 & frequency response differences between 2SC5551 and 2SC3357.?
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I used the circuit model that I previously developed for my prototype LZ1AQ and detailed in message #20829. The 2SC3357 model is from NEC, while the 2SC5551 model is from LTWiki. The latter is just the chip model & does NOT include the SOT-89 package parasitics. However, I suspect the package parasitics can be ignored at HF.?
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In the IP3 comparison, 2SC3357 (blue) beats 2SC5551 (green) by ~1 dB, while 2N2222A (red) is 3~4 dB lower than the rest. I am surprised that the 2N2222A is so much poorer, because, in general, IP3 is a function of the supply current and the 3 BJTs have almost similar simulated Icc values.?
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Frequency response: 2SC5551 (green) and 2SC3357 (blue) traces nearly overlapped. Again, the 2N2222A (red) is clearly inferior to the other two; ~4 dB lower gain at the 29 MHz peak.
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73, Leong, 9M2LCL, ex-9W2LC.?
